Collapsible muffler system

ABSTRACT

The muffler system of the preferred embodiment includes an outer membrane adapted to operate in a collapsed mode, wherein the outer membrane defines a first volume that facilitates portability and stowage, and in an expanded mode, wherein the outer membrane defines a second volume, which is larger than the first volume, that provides attenuation and muffling of the noise signature of the power system. The muffler system further includes an inlet coupled to the outer membrane and adapted to allow the exhaust gases and sound waves from the portable power system to enter the muffler system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/755,520, filed 31 Dec. 2005 and entitled “Collapsible Muffler System”, which is incorporated in its entirety by this reference.

TECHNICAL FIELD

This invention applies to the field of muffler systems and, more specifically, to a low-acoustic-signature muffler system for a portable power system.

BACKGROUND

Conventional portable power systems have very high noise levels and large acoustic signatures during operation. Although users such as fisherman and military personnel desire quieter power systems, conventional muffler systems cannot meet both the requirement of a small volume to provide adequate portability and stowage of the power system, and the requirement of a large volume to provide adequate attenuation and muffling of the noise signature of the power system. This invention provides a new and useful muffler system that meets both of these requirements.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B are perspective views of the preferred embodiment of the invention, shown in a collapsed mode and an expanded mode, respectively.

FIGS. 2A and 2B are perspective views of a second variation of the preferred embodiment of the invention, shown in a collapsed mode and an expanded mode, respectively.

FIGS. 3A and 3B are perspective views of a third variation of the preferred embodiment of the invention, shown in a collapsed mode and an expanded mode, respectively.

FIGS. 4A, 4B, and 4C are perspective views of a fourth variation of the preferred embodiment of the invention, shown in a collapsed mode, shown transitioning from a collapsed mode to an expanded mode, and shown an expanded mode, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment of the invention is not intended to limit the invention to this preferred embodiment, but rather to enable any person skilled in the art to make and use this invention.

As shown in FIG. 1A and 1B, the muffler system 10 of the preferred embodiment includes an outer membrane 12 adapted to operate in a collapsed mode and an expanded mode and an inlet 14 coupled to the outer membrane 12 and adapted to allow the exhaust gases and sound waves from the portable power system to enter the muffler system 10.

As shown in FIGS. 3 and 4, the muffler system 10 may further include a frame structure 16 coupled to the outer membrane 12 and adapted to operate in a collapsed mode and an expanded mode, an outlet 18 coupled to the outer membrane 12 and adapted to allow the exhaust gases to exit the muffler system 10, a first end cap 20 coupled to the inlet 14 and/or the outlet 18, a second end cap 22 coupled to the inlet 14 and/or the outlet 18, a securing element 24 coupled to the outer membrane 12 and/or the frame structure 16 and adapted to hold the outer membrane 12 in the expanded mode, an inner exhaust pipe 26 coupled to the inlet 14 and the outlet 18 and adapted to allow the exhaust gases and sound waves from the portable power system to travel through the muffler system 10 and to aid in the attenuation and muffling of the noise signature, a self-deployment device coupled to the outer membrane 12 and/or the frame structure 16 and adapted to automatically expand the outer membrane 12 from the collapsed mode to the expanded mode, and a catalytic converter adapted to expose the exhaust gases from the portable power system to a catalyst.

The muffler system 10 is preferably designed for the use with a power system and, more specifically, for the use with a portable power system having a noise signature. The muffler system 10 of the preferred embodiment has been specifically designed to provide adequate portability and stowage in a collapsed mode, and to provide adequate attenuation and muffling of the noise signature of the power system in the expanded mode (>40 dB). The collapsed mode is preferably equal to or less than 50%, and more preferably equal to or less than 20%, of the volume of the expanded mode. The muffler system 10, however, may be alternatively used in any suitable environment and for any suitable reason.

The outer membrane 12 of the preferred embodiment functions to operate in a collapsed mode, as shown in FIG. 1A, and an expanded mode, as shown in FIG. 2B. In the collapsed mode, the outer membrane defines a first volume that facilitates portability and stowage. In the expanded mode, the outer membrane defines a second volume, which is larger than the first volume, that provides attenuation and muffling of the noise signature of the power system. Additionally, the outer membrane 12 functions to absorb the sound waves. The outer membrane 12 may be constructed in multiple layers of different materials, such as two thin layers of metal or plastic material that sandwich a layer of an insulating material, or may alternatively be constructed in any suitable fashion such that the outer membrane 12 will absorb some of the sound waves. The outer membrane 12 is preferably designed to function in the frequency range where the power system makes the most noise. The outer membrane 12 in the expanded mode may function in any suitable manner as to provide adequate attenuation and muffling of the noise signature of the power system.

The outer membrane 12 is preferably one of several variations. In a first variation, as shown in FIGS. 1-3, the outer membrane 12 is made out of a plastic, canvas, rubber, or any other suitable flexible and durable material. In this variation, the outer membrane 12 in the collapsed mode (shown in FIG. 1A, 2A, and 3A) is preferably deflated, but may alternatively be in any other suitable collapsed or compressed mode. In this first variation, the outer membrane 12 is adapted to transition from the collapsed mode to the expanded mode by inflating. Upon inflation, the outer membrane 12 fills with air (with or without stretching) into the expanded mode. The outer membrane 12 is preferably inflated by air or exhaust from the power system, but may alternatively be inflated in any other suitable manner in order to transition from the collapsed mode to the expanded mode (shown in FIGS. 1B, 2B, and 3B).

In a second variation, as shown in FIG. 4, the outer membrane 12 is preferably made out a plastic, canvas, rubber, or any other suitable foldable material or alternatively made out of a metal, plastic, or any other suitable rigid material with panels or creases. In this second variation, the outer membrane 12 is adapted to transition from the collapsed mode (shown in FIG. 4A) to the expanded mode (shown in FIG. 4B) by unfolding.

In a third variation, the outer membrane 12 includes a shape memory material and transitions from the collapsed mode to the expanded mode by changing shape due to the application of an external stimuli such as temperature, light, electricity, mechanical stress, or any suitable stimuli. In this variation, the outer membrane 12 will be in a collapsed shape and upon the application of an external stimuli, the shape of the outer membrane will change to a larger, expanded shape.

The outer membrane 12 preferably has an elliptical or circular cross-section, but may alternatively be any suitable shape, size, and thickness. The outer membrane 12 preferably transitions from the collapsed mode to the expanded mode by expanding axially, but may alternatively expand radially, expand axially while decreasing in size radially or vice versa, expand by untwisting, expand into a dome shape, as shown in FIG. 2B, or may increase the volume defined by the outer membrane 12 in any other suitable manner. Although the outer membrane 12 is preferably one of these multiple variations, the outer membrane 12 may be any suitable membrane to provide adequate portability and stowage in a collapsed mode, and to provide adequate attenuation and muffling of the noise signature of the power system in the expanded mode. In alternative variations, the muffler system 10 may include any suitable combination or permutation of the above outer membranes 12.

As shown in FIGS. 1, 2, and 3, the inlet 14 of the preferred embodiment functions to allow the exhaust gases and sound waves from the portable power system to enter the muffler system 10. Preferably, the inlet 14 includes at least one port adapted to couple to the portable power system. Alternatively, the inlet 14 may be a pipe or any other suitable conduit with holes or other suitable perforations for the exhaust gases and sound waves entering the muffler system 10 from the portable power system. The inlet 14 is preferably made out of metal, but may alternatively be made out of any other suitable, durable material such as plastic or rubber. The inlet 14 is preferably made with conventional techniques in the art, but may alternatively be made with any suitable methods.

As shown in FIGS. 3 and 4, the muffler system 10 of the preferred embodiment may further include a frame structure 16 coupled to the outer membrane 12. Like the outer membrane 12, the frame structure 16 of the preferred embodiment functions to operate in a collapsed mode and in an expanded mode. In the collapsed mode, the frame structure 16 defines a first volume that facilitates portability and stowage. In the expanded mode, the frame structure 16 defines a second volume, which is larger than the first volume, and provides structure for the outer membrane. The frame structure 16 is preferably one of several variations. In a first variation, the frame structure 16 includes telescoping rods adapted to transition from the collapsed mode to the expanded mode by lengthening telescopically. The telescoping rods in this variation are preferably made out of metal or plastic or any other suitable material. In a second variation, the frame structure 16 includes a spring adapted to bias the outer membrane from the collapsed mode to the expanded mode. The spring in this variation is preferably a helical spring, but may alternatively be a wave spring or any other suitable spring geometry, made out of metal, plastic, a shape memory material, or any other suitable material.

In a third variation, the frame structure 16 includes a shape memory material adapted to transition from the collapsed mode to the expanded mode by changing shape due to the application of an external stimuli such as temperature, light, electricity, mechanical stress, or any suitable stimuli. The frame structure 16 in this variation is preferably a mesh geometry, but may alternatively be a helical geometry or any other suitable geometry that can expand from a collapsed mode to an expanded mode by changing shape.

In a fourth variation, as shown in FIG. 3, the frame structure 16 includes multiple rings that transition from the collapsed mode to the expanded mode by separating. The rings of this variation, compress down, minimizing the distance between each ring, as shown in FIG. 3A, to operate in the collapsed mode. As shown in FIG. 3B, the distance between each of the rings increases to transition the frame structure 16 from the collapsed mode to the expanded mode. The rings in this variation may be made out of metal, plastic, or any other suitable material.

In a fifth variation, as shown in FIG. 4, the frame structure includes multiple poles. The poles of this variation provide rigidity to the outer membrane 12, framing multiple panels that are adapted to transition from the collapsed mode to the expanded mode by unfolding. In this variation, the frame structure 16 may alternatively function similarly to conventional tent poles. The poles may be inserted or coupled to a flexible outer membrane 12 to expand the outer member from the collapsed mode to the expanded mode.

The frame structure 16 preferably transitions from the collapsed mode to the expanded mode by expanding axially, but may alternatively expand radially, expand axially while decreasing in size radially or vice versa, expand by untwisting, or may increase the volume defined by the frame structure 16 in any other suitable manner. Although the frame structure 16 is preferably one of these multiple variations, the frame structure 16 may be any suitable frame structure to provide adequate portability and stowage in a collapsed mode, and to provide adequate attenuation and muffling of the noise signature of the power system in the expanded mode. In alternative variations, the muffler system 10 may include any suitable combination or permutation of the above frame structures 18.

As shown in FIGS. 1, 2, and 3, the outlet 18 of the preferred embodiment functions to allow the exhaust gases to exit the muffler system 10. Preferably, the outlet 18 is a port adapted to couple to the portable power system. Alternatively, the outlet 18 may be a pipe or any other suitable conduit for the exhaust gases exiting the muffler system 10. The outlet 18 is preferably made out of metal, but may alternatively be made out of any other suitable, durable material such as plastic or rubber. The outlet 18 is preferably made with conventional techniques in the art, but may alternatively be made with any suitable methods.

As shown in FIGS. 2, 3, and 4, the muffler system 10 of the preferred embodiment may also include a first end cap 20 coupled to the inlet 14 or, as shown in FIG. 2, coupled to both the inlet 14 and the outlet 18. As shown in FIGS. 3 and 4, the muffler system 10 of the preferred embodiments may also further include a second end cap 22 coupled to the outlet 18, as shown in FIG. 3, or coupled to both the inlet 14 and the outlet 18. The first end cap 20 and the second end cap 22 function to add stability to the muffler system 10. The end caps may additionally be coupled to the outer membrane 12 and/or the frame structure 16 such that the frame structure 16 extends from the first end cap 20 to the second end cap 22. The end caps are preferably a metal cap of any suitable shape, but may alternatively be any other suitable durable material such as plastic or rubber. The end caps may be constructed such that they aid in the absorption of sound waves. The end caps may be constructed in multiple layers of different materials, preferably including two thin layers of metal or plastic sandwiching a layer of an insulating material. The end caps may alternatively be constructed in any suitable fashion such that the end caps will absorb some of the sound waves.

As shown in FIG. 3, the muffler system of the preferred embodiment may also include a securing element 24 coupled to the outer membrane 12, the frame structure 16, the first end cap 20, and/or the second end cap 22. The securing element 24 functions to secure the muffler system 10 in the collapsed mode, the expanded mode, or both. The securing element 24 is preferably one of several variations. In a first variation, as shown in FIG. 3, the securing element 24 includes multiple tension rods for the expanded mode, coupled to the first end cap 20 and the second end cap 22 which function to hold apart the end caps. The tension rods may be selectively attached to the muffler system 10, or may alternatively be telescopic rods, springs, or elements expandable in any other suitable manner. The securing element 24 is preferably made of metal, but may be alternatively made from any suitable rigid material. In a second variation, the securing element 24 is a clasp for the collapsed mode, which functions to secure the muffler system 10 in the collapsed mode. The securing element 24 is preferably a hook coupled to the first end cap 20 and a eyelet coupled to the second end cap 22 which functions to hold the muffler system 10 in the collapsed mode by securing the first end cap 20 a set distance from the second end cap 22. The securing element 24 may alternatively be a spring, a tie, or any other suitable clasp to hold the muffler system 10 in the collapsed mode.

As shown in FIG. 3, the muffler system 10 of the preferred embodiment may also include an inner exhaust pipe 26. The inner exhaust pipe 26 is coupled to the inlet 14 and the outlet 18 and functions to allow the exhaust gases and sound waves from the portable power system to travel through the muffler system 10 and to aid in the attenuation and muffling of the noise signature. Preferably, the inner exhaust pipe is a metal pipe but may alternatively be any suitable conduit of any suitable material to allow the exhaust gases and sound waves from the portable power system to travel through the muffler system 10. The inner exhaust pipe 26 may also be perforated with holes. The sound waves will exit the inner exhaust pipe 26 into the muffler system 10 through the holes. The holes are adapted to divide the sound waves into multiple smaller sound waves. The smaller waves will then bounce around in the volume defined by the outer membrane 12, canceling each other out and also being absorbed by the outer membrane 12. The inner exhaust pipe 26 is preferably made with conventional techniques in the art, but may alternatively be made with any suitable methods. In a first variation, as shown in FIG. 3, the inner exhaust pipe 26 is a single, straight pipe. In a second variation, the volume defined by the outer membrane 12 may contain multiple chambers. In this variation, the inner exhaust pipe 26 may include a series of multiple pipes, in series and/or in parallel, connecting the multiple chambers of the muffler system 10 and allowing the exhaust gases and sound waves from the portable power system to travel through the multiple chambers of the muffler system 10. The inner exhaust pipe 26 may be straight with a circular cross section, but may alternatively be curved or in any suitable orientation with any suitable cross section geometry.

In an alternative embodiment, the muffler system 10 also includes a self-deployment device. The self-deployment device functions to automatically transition the outer membrane and/or the frame structure 16 from the collapsed mode to the expanded mode. The self-deployment device may further function to automatically transition the outer membrane and/or the frame structure 16 from the expanded mode to the collapsed mode. In one variation, the self-deployment device includes a thermo-mechanical method to use the exhaust heat of the portable power system to thermally expand the collapsible muffler to its operating mode. In this variation, the outer membrane 12 and/or the frame structure 16 may be made out of a shape memory material. The self-deployment device will apply external stimuli such as temperature, light, electricity, or mechanical stress causing the outer membrane 12 and/or the frame structure 16 to change shape and move from the collapsed mode to the expanded mode. In a second variation, the self-deployment device is adapted to use air or exhaust gases to inflate the outer membrane 12 and/or the frame structure 16 from the collapsed mode to the expanded mode. In another variation, the self-deployment device includes an electromechanical method to use a small, low power, electric motor to drive central lead screw that will expand and collapse the outer membrane 12 and/or frame structure 16 to achieve either the stowed-volume in the collapsed mode or the operating volume in the expanded mode.

In an alternative embodiment, the muffler system 10 also includes a catalytic converter. The catalytic converter functions to catalytically convert at least a portion of any unburnt or partially oxidized fuel and oxidants. The preferred catalytic converter facilitates portability and stowage. With the inclusion of a catalytic converter, the portable power system may have a reduced emission signature, which may allow the portable power system to be used in an enclosed space such as a room, a boat cabin, or a vehicle cabin. The catalytic converter is preferably formed as a spiral or helical member with a collapsible membrane or porous media. Additionally, the catalytic converter may be constructed in a honeycomb structure or may include ceramic beads. The catalytic converter may, however, be formed as any suitable member with any suitable material such that the maximum surface area of catalyst is exposed to the stream of exhaust gases, while also minimizing the amount of catalyst required. The catalytic converter is preferably made with conventional techniques in the art, but may alternatively be made with any suitable methods.

The elements of the muffler system 10 in the expanded mode preferably function as a conventional muffler, where the sound waves from the power system bounce around the volume defined by the outer membrane 12, canceling each other out, and additionally are absorbed by the outer membrane 12. The muffler system 10 in the expanded mode may alternatively function in any other suitable manner as to provide adequate attenuation and muffling of the noise signature of the power system. For example, the muffler system 10 may function similarly to a glass pack or a cherry bomb, which use absorption only to reduce the sound of the power system.

Although omitted for conciseness, the preferred embodiments include every combination and permutation of the various outer membranes 12, the various inlets 14, the various frame structures 16, the various outlets 18, the various first end caps 20, the various second end caps 22, the various securing elements 24, the various inner exhaust pipes 26, the various self-deployment devices, and the various catalytic converters.

As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiment of the invention without departing from the scope of this invention defined in the following claims. 

1. A muffler system for a portable power system having a noise signature, comprising: an outer membrane adapted to operate in the following modes: collapsed mode, wherein the outer membrane defines a first volume that facilitates portability and stowage; and expanded mode, wherein the outer membrane defines a second volume, which is larger than the first volume, that provides attenuation and muffling of the noise signature of the power system; and an inlet.
 2. The muffler system of claim 1 wherein the first volume is equal or less than 50% of the second volume.
 3. The muffler system of claim 2 wherein the first volume is equal or less than 20% of the second volume.
 4. The muffler system of claim 1 wherein the outer membrane is adapted to transition from the collapsed mode to the expanded mode by inflating.
 5. The muffler system of claim 1 wherein the outer membrane includes creases and is adapted to transition from the collapsed mode to the expanded mode by unfolding.
 6. The muffler system of claim 1 wherein the outer membrane includes a shape memory material and is adapted to transition from the collapsed mode to the expanded mode by changing shape due to the application of at least one of temperature, light, electricity, and mechanical stress.
 7. The muffler system of claim 1 further comprising a frame structure coupled to the outer membrane and adapted to operate in the following modes: collapsed mode, wherein the frame structure defines a first volume that facilitates portability and stowage; and expanded mode, wherein the frame structure defines a second volume, which is larger than the first volume, and provides structure for the outer membrane.
 8. The muffler system of claim 7 wherein the frame structure includes telescoping rods adapted to transition from the collapsed mode to the expanded mode by lengthening telescopically.
 9. The muffler system of claim 7 wherein the frame structure includes a spring adapted to bias the outer membrane from the collapsed mode to the expanded mode.
 10. The muffler system of claim 7 wherein the frame structure includes a shape memory material and is adapted to transition from the collapsed mode to the expanded mode by changing shape due to the application of at least one of temperature, light, electricity and mechanical stress.
 11. The muffler system of claim 7 wherein the frame structure comprises a plurality of rings adapted to transition from the collapsed mode to the expanded mode by separating.
 12. The muffler system of claim 7 further comprising an outlet and a first end cap coupled to the outer membrane and coupled to at least one of the inlet and the outlet.
 13. The muffler system of claim 12 further comprising a second end cap coupled to the outer membrane and coupled to at least one of the inlet and the outlet.
 14. The muffler system of claim 13 wherein the frame structure extends between the first end cap and the second end cap.
 15. The muffler system of claim 7 further comprising a securing element adapted to hold at least one of the outer membrane and the frame structure in at least one of the collapsed mode and the expanded mode.
 16. The muffler system of claim 7 further comprising a self-deployment device adapted to transition at least one of the outer membrane and the frame structure from the collapsed mode to the expanded mode.
 17. The muffler system of claim 16 wherein the self-deployment device is adapted to use heat to expand at least one of the outer membrane and the frame structure from the collapsed mode to the expanded mode.
 18. The muffler system of claim 16 wherein the self-deployment device is adapted to use air to inflate at least one of the outer membrane and the frame structure from the collapsed mode to the expanded mode.
 19. The muffler system of claim 16 wherein the self-deployment device includes an electric motor to drive at least one of the outer membrane and the frame structure from the collapsed mode to the expanded mode.
 20. The muffler system of claim 1 further comprising a catalytic converter adapted to expose the exhaust from the portable power system to a catalyst. 